Studies in dogs exhibiting sodium retention suggest that the renal nerves play a major role in the efferent pathway mediating the increased renal sodium reabsorption. We have performed studies showing that renal denervation prevents the antinatriuresis seen with constriction of thoracic inferior vena cava in dogs. Glomerular filtration rate was unchanged but renal blood flow, renal perfusion pressure and cardiac index were decreased. Although these data support the conclusion that the renal nerves participate in the mediation of the antinatriuresis, they do not elucidate the intra-renal mechanism of this action. We propose, applying micropuncture techniques for measuring single nephron glomerular filtration rate, intratubular pressure and segmental sodium handling with a method for measuring the intrarenal distribution of blood flow, to study the role of the renal nerves in sodium retaining states in the intact dog kidney.